Here is the sound of a 50-caliber Barrett rifle being fired. You'll first hear the sound of the bolt being pulled back. Really cool sound if you can listen on some nice big speakers.

Recorded with my Handy Zoom H4N using a Rode NTG-2 shotgun microphone. I was standing about 20 feet from the rifle, and I still have the input gain turned way down to about 30, just to make sure the circuitry was not overloaded. Also, since this was in a big, wide-open field, you get a nice echo.